Rocklin et al. U.S. Pat. No. 3,026,264 describes the antioxidant use of several 3,5-dialkyl-4-hydroxybenzyl-substituted benzenes such as 2,4,6-tri(3,5-di-tert-butyl-4-hydroxybenzyl)mesitylene. They are made by the reaction of 2,6-dialkyl-4-hydroxymethyl phenots with a benzene compound in an inert solvent at -15 to 100.degree. C. in the presence of sulfuric acid or a Friedel Crafts catalyst.
Gurvich et al. G.B. No. 1,327,542 discloses a process for making 2,4,6-tri(3,5-dialkyl-4-hydroxybenzyl)benzenes by reacting a 2,6-dialkyl-4-methoxymethyl phenol with an alkylbenzene compound in an inert solvent in the presence of an acidic catalyst such as sulfuric acid. In Examples 1, 3, and 4, Gurvich et al. uses 364 parts by weight 94% sulfuric acid per mole part mesitylene. In a commercial operation this presents a severe spent sulfuric acid disposal problem. However, merely reducing the amount of sulfuric acid results in a reaction wherein less than all of the reactive positions on the benzene compound become substituted. In the case of mesitylene and 2,6-di-tert-butyl-4-methoxymethyl phenol, lowering the amount of sulfuric acid gives a product which contains both mono- and di-3,5-di-tert-butyl-4-hydroxybenzyl-substituted mesitylene by-products, making it unacceptable for commercial sale. Thus, a need exists for a process which allows reduction in the amount of sulfuric acid used as catalyst and at the same time gives a product suitable for commercial use.